One sniper amid thousands of tips

Police must sift, track and frequently rule out clues in huge manhunt

One was a Rockville man who disappeared two days before the sniper attacks began. He had recently purchased a .223-caliber rifle, and he drove a white van with a ladder on top. A recovering drug addict, he had recently accumulated large debts.

Another was a former Marine from Baltimore with a white Chevrolet Astro van whose enthusiasm for firearms was shared by his girlfriend. Investigating the couple after a domestic shooting, police found several guns and other tantalizing clues: a manual for snipers and a misspelled note declaring "Gihad in America."

But after hours of excited news media reports about a possible sniper suspect in custody, first on Oct. 5 and then again Monday, police in both cases abruptly ended the building suspense: Neither man was the Washington-area sniper responsible for killing nine people and wounding two.

The seemingly promising leads were unusual, though, only because they became public. While the search for the sniper has drawn far more attention and resources than most homicide investigations, the case is unfolding behind the scenes in many ways just like any other.

Investigators have dangled rewards, interviewed witnesses and - though sparingly - gone public with concrete tips such as yesterday's release of two composite sketches of white minivans that could be linked to the shootings. They look for motives, knock on doors and try to knock down, or substantiate, the many theories about the mysterious sniper.

"Every dead end you get is one less person you have to investigate," said Brian H. Levin, a criminal justice professor at California State University, San Bernardino. "The process of elimination is every bit as important as the process of fulfillment."

Beyond the two men who briefly faced a torrent of public scrutiny, investigators have looked at dozens of other potential suspects who at first looked intriguing but quickly were ruled out. Montgomery County Police Chief Charles Moose told reporters that as investigators question individuals, "many, many of these people have been eliminated as suspects."

Criminologists say that is the most basic work of any criminal investigation. But it is made difficult in cases that are extremely high profile and complex, and the unsolved sniper shootings fit both descriptions.

Investigators in the sniper case are using an FBI computer program called Rapid Start to collect and catalog more 2,000 credible leads, culled from many thousands of tips. The high-tech tool, used in such complex investigations as the bombings at Oklahoma City's federal building in 1995 and at the World Trade Center in 1993, lets investigators quickly cross-reference information to find connections that otherwise might go unnoticed.

Officials have taken the familiar step of asking anyone with information about the white van described at Monday's shooting scene to come forward. They also are able to use another computer tool to generate all of the license plate numbers that would match the partial description offered by witnesses.

Investigators who have worked previous serial killer cases say success depends heavily on information management: categorizing and prioritizing the mountain of minutia pouring in every day from do-gooders, cranks and cops in the field.

`We were inundated'

Joseph J. Coffey, who led the investigation of the Son of Sam serial killer case, quickly learned that lesson. "We were inundated," said Coffey, now 64 and retired. "We had girlfriends giving up boyfriends, husbands giving up wives, mothers giving up sons."

In the days before computers, Coffey says investigators relied on filing cabinets, shoe boxes and luck to catch David Berkowitz, who was convicted of killing six New Yorkers and wounding seven others between July 1976 and August 1977. A neighbor and a co-worker had called in tips about Berkowitz, but it was a routine parking ticket that finally placed him near one of the crime scenes.

When a sniper struck in July 1994 on Long Island, N.Y., killing one person and wounding two others over 13 days, the Suffolk County Police Department ultimately combed through more than 200,000 tips.

Assistant Chief John McElhone, who helped coordinate the manhunt, said investigators built a computer database to handle the flood of leads generated by the some 300 officers who worked the case, knocking on 2,650 doors and questioning 4,100 people.

They fed the database with the name of every owner of every weapon confiscated in an arrest; the names of speeders, parking violators and parolees; and any patient recently released from a mental hospital. Then they added in every phone tip.

"You hope that each one is going to be the one," McElhone said. "People are dying and you want to stop it."

Inevitably, police wasted time on bad leads, he said. In the end, though, police linked a gun used by the killer to an auto-body deliveryman, Peter Sylvester, whose name had been entered into the computer a few months earlier after a routine arrest on a parole violation.